ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



535 



about a vertical axis. The mirror is rotated in the direction of the 

 arrow, and at an angle less than 45° throws the image on to M. Another 

 view of it is seen in fig. 58. Fig. 59 gives a general view of the whole 

 instrument. 



y . , ' ; '/•* 



Fig. 58. 



I 



Fig. 59. 



